a. Field of Invention
The invention relates generally to vehicle structural design, and, more particularly, to a vehicle hood design for permitting generally predetermined hood deformation during a front impact event.
b. Description of Related Art
The front body of a vehicle generally includes a frame, a front bumper system, body panels, and a hood mounted to the body structure for allowing access to the engine compartment. During a front impact event, amongst other components, the front bumper system, body panels and hood are each designed to absorb a predetermined percentage of the impact, which is generally in direct correlation with the deformation characteristics of such components. Thus, the design of the front body plays an important role in the absorption and distribution of forces generated during a front impact event.
While hoods normally include a smooth upper (i.e. exposed) surface, some existing hood designs include a variety of contours on the visible hood side for primarily providing a desired aesthetic appearance. Such contours are generally provided on a hood outer panel which is welded or otherwise attached to an inner panel including a variety of structural beams for allowing predetermined hood deformation, as well as for providing stiffness to the hood structure. Such contours on the outer panel however also affect the hood deformation characteristics during a front impact event.
For example, referring to FIG. 1 (a), an exemplary hood design is illustrated and includes a hood 10 having an outer panel 12. As can be seen in FIG. 1(a), the outer panel includes a generally smooth outer surface. However, referring to FIG. 2(a), as discussed in detail below, a hood design according to the present invention includes a pair of raised longitudinal sections 14 equally spaced from the centerline of the vehicle (not shown). The raised sections each intersect with an equally raised section 16 that runs along the rear (lateral) edge 18 of the hood. This design creates a “reverse power dome” in center portion 20 of the outer panel, thus providing the hood with a desirable aesthetic appearance.
As shown in FIG. 1 (b), in order to prevent hood windshield intrusion during a front impact event, for the hood structure of FIG. 1 (a) which includes a smooth outer panel surface, it is known to provide a single set of crush initiators 22 (or a single crush initiator 22 as shown in FIG. 1(a)) on inner panel 24 generally centrally along the hood longitudinal direction. During a front impact event, this type of hood structure results in “A” shaped deformation of the hood (when viewed from the side of the deformed hood), which for conventional hood designs such as the design of FIG. 1(a), provides acceptable deformation characteristics. However, for a hood which includes the reverse power dome feature of FIG. 2(a), as well as other similar contours on the hood outer panel, during a front impact, the raised sections 14 and 16 may act as beams to potentially intrude into a windshield during the front impact event. Moreover, the reverse power dome feature has a natural tendency to buckle in a downward direction toward the vehicle engine (not shown), which is also undesirable.
It would therefore be of benefit to provide a vehicle hood structure which allows for the inclusion of a variety of contours on the hood outer panel, such as the noted reverse power dome feature, without affecting the deformation characteristics of the hood. It would also be of benefit to provide a hood structure capable of predetermined deformation during a front impact event, with the hood structure meeting existing automotive hood deformation requirements, without significantly increasing the design, tooling and manufacturing costs for such structural components.